Histoplasmosis Facts (cont.)

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

What causes histoplasmosis?

The causative organism is a fungus, Histoplasma capsulatum. The fungus is
often found in association with bird or bat droppings in the environment. When
the microscopic fungal spores are inhaled, some people develop an illness
similar to pneumonia. Not everyone who inhales the spores develops the illness.
The spores may become airborne in demolition projects in areas that contain bat
or bird droppings. The airborne spores can travel hundreds of feet. It has been
estimated that in the U.S. around 250,000 people are infected each year.

Histoplasma capsulatum can be found throughout the world, but it is most
commonly located in North and Central America. Within the U.S., it is particularly
common in the Ohio and Mississippi River valleys. In areas where the fungus is
common, between 50%-80% of people will show an antibody response to the
organism, meaning that they have been exposed to the fungus at some point in
their life.

What are risk factors for histoplasmosis?

Anyone may develop histoplasmosis. However, the illness is more likely to
occur in infants, young children, and the elderly. People with suppressed immune
function or chronic lung disease are also at increased risk for severe
(disseminated) disease. The soil may also become contaminated with the fungus,
so those who work with soil, such as landscapers and farmers, are at greater
risk. Also at risk are workers performing demolition work in areas that may be
contaminated with bird or bat droppings.

What are histoplasmosis symptoms and signs?

As mentioned before, not everyone who inhales the fungal spores becomes sick.
When illness does occur, the signs and symptoms appear anywhere from three to 17
days after exposure. The symptoms are similar to pneumonia and include fever,
chills, sweats, a dry cough, malaise, and chest pains. Some affected people also
experience joint pains.

If these disease progresses without treatment, those affected may develop
weight loss, shortness of breath, and fatigue. Ocular involvement in
disseminated disease can cause loss of vision. If the infection spreads to the
central nervous system, severe symptoms including seizures, headaches, and
confusion may develop.